QTR-Quadtone RIP

I've used QTR only for working with additional papers and my quad
Piezography inkset on my 7000. I tried toying with creating a "color"
B&W profile with my Epson 4000. . . and it was a dismal failure. Are
the only inks used the PK or MK blacks and the Light Black? Do the
magenta/cyan et al only come into play when creating slightly toned
versions? I tried several variations, using the yellow and the LM and
LC inks, but the highlights were always toned yellow, or whatever.
Also the  80-90% black was always much deeper and richer than 100% --
I suppose because of the added colors, not unlike "rich black" in
offset printing.

Thanks for pointing me in the right direction.

Nemo